Treatment of cellulose derivative articles



or wet steam or hot water.

Patented Oct. 16, 1945 UNITED STATES PATENT issues OFFICE TREATMENT OFCELLULOSE DERIVATIVE ARTICLES No Drawing. Application March 17, 1943, Serial No. 479,492. In Great Britain March}, 1942 4 Claims.

This invention is concerned with improvements in the treatment of cellulose derivative articles and particularly in processes for improving the physical properties of yarns, foils and similar articles made of cellulose acetate or other orthe presence of'a suitable assisting agent, which may be an organic solvent, for example dioxane, The yarns may be stretched, for instance, to 500 or 1,000% of their original length according to the increase in tenacity which is required and in this manner yams having a tenacity of 3 r 4 grams per denier or more may be obtained. Yarns made of-high viscosity cellulose acetate, e. g. an acetate having a viscosity of 80-100, measured by comparing the rate of flow of a 6% solution of the acetate in acetone-with that of glycerine taken as 100,.

may after stretching have a tenacity as high as it has been found possible in this manner to increase the extension up to 10 or 2% or somewhat more but only at the cost of some or the 1 increase in tenacity produced by the stretching operation.

It has now been discovered that very good re sults may be obtained as regards improvement in the extensibility of yarns, foils and similar articles made of organic derivatives of particularly acetone-soluble cellulose acetate, without causing substantial loss intenacity, by impregnating them with a medium containing a cyclic ketone, partici'iarly cyciopentanone, without subjecting them to tension suiiicient to stretch them. Preferably the treatment is ei-=' .fected under such conditions that'a low degree of shrinkage is efi'ected, e. g. 12-10% of the original length of the materials.

The process of the present invention is of greatest importance in connection with the 'im- I provement of the extensibility of yarns and similar articles, for example cords, made of cellulose acetate or other lower fatty acid ester of eel-- lulose, for, example cellulose propionate, cellulose butyrate and cellulose acetate-propionate. The

materials treated may be made of a cellulose derivative of low, medium or high viscosity. For instance, the process is applicable to the treatment of yarns made of cellulose acetate having a viscosity of 10, 20, 80,100 or more, determined as described above.- The process is most valuable for the treatment of yarns and similar materials which have been stretched, e.-g. to 2, 6, 10 or more times their original length, so as to increase their tenacity, for example to 2, 3, 4 or more grams per denier, since, as explained above, such articles usually have an extensibility lower than that desirable for many purposes, for example an extensibility of 6, 8 or 10%. The best results areusually obtained with materials which have been stretched, especially in hotwater or 'wet steam, to between? and 5 times their original length; The process is also appliper denier, although as-such yarns usually have an extensibility of 20-25% or even more, it is not for most purposes necessary to increase it cellulose,

present in petrol, ligroin, berm ne further. v

'Cyclopentanone has been employed with very good results in the process of the invention, particularly where the materials treated are made of acetone-soluble cellulose acetate or other lower fatty acid ester of cellulose. Other cyclic ketones may however be employed, preferably ones which are liquid at atmospheric temperature, for ex, ample, cyclobutanone, cyclohexanone and the .methyl-cyolopentanones and cyclohexanones.

The cyclic ketones are preferably employed in solution in organic liquids which themselves have no action on the cellulose derivative forming the basis of the materials under treatment. Such inert liquids include the liquid paramn hydrocarbons and diethyl ether and other ethers. Mixtures of parafiin hydrocarbons such as are and kerosene maybe employed.

It has been found; that theshrinking effect the cyclic ketones is greatly enhanced by the presence of small proportions of water. For

2 example, the shrinking action of a 50% 01 tion or cyclopentanone in petrol on stretched cellulose acetate yarn may be increased 5 to original length was treated in bank form in a solution containing 30% of cyclopentanone and 70% petrol by volume at 25 C. for 30 minutes.

times by the presence or .2-.5 of water inthe mixture. It is therefore very importa'nt'to control the water content, if any, of the shrinking liquid'if consistent results are to be obtained. Usually it is preferable to use an anhydrous solution and to dry the yarn or other materials before treatment.

The concentration of the cyclic ketone, th treatment temperature and the time of treatment are all inter-related and a variation in one factcrusually involves some variation in one or both of the others in order to obtain the optimum results. When yarns or other articles are treated in batches the treatment may, for example, be carried out using cyclopentanone dissolved in for about -30 minutes. If it is desired to carry out the treatment as a continuous processit is usually preferable to accelerate the action of the cyclic ketoneby raising the temperature of the v cellulose acetate may be treated by passing them through a 50% solution of cyclopentanone in travel of the yarnsand the length of the bath being so arranged that they are .in contact with the shrinking liquid for about 30-60 seconds.

to remove all traces both of the cyclic ketone and fected by washing them first with ether, drying them, giving them a light scour in a very dilute soap solution andthen washing them in water,

, After the treatment has been compltted the materials may be completely saponifled, e. g. with a .6%' solution or sodium hydroxide containing 10% of sodium acetate at 60% C. Regentenacity are thus obtained.

The following examples are given to'illustrate theinvention.) i

Example I soluble cellulose acetate was treated in hank form in a solution containing38% of cyclopentanone and 62%. of petrol by volume, for 30 minutes at 25 'C. It was then thoroughly washed in ether, dried, given a light scour in .02% soap solution for 5 minutes at 60 C. washed in water, dried and conditioned; The yarn obtainedha'd a substantenacity as before the treatment. Example II A yarn made of acetone-soluble cellulose ace- 'An' ordinary dry-spun yarn made of acetonetate and stretched in wet steam to 5 times its.

petrol in a concentration of 30-55% at 20-40" 0.

solution employed. For'example, yarns made of.

petrol at a temperature of 50-60" C., the rate of It is important that the materials should be thoroughly washed after the treatment in order of the diluent employed. Preferably this .is eiafter which they may be dried and-conditioned. I

- chloride.

evaporation are not high. Moreover on account. ,v

of their hydrophile character they are much more easily removed from the materials by scouring than are shrinking'agents such as methylene A particular advantage of cyclopentanone is that the conditions required in order to obtain good results are not so critical as in the case of many shrinking agents.v

Having described our invention what we desire to secure by Letters Patent is:

1. Process for the treatment of artificial yarns,

foils and similar materials, which comprises impregnating stretched yarns, foils and similar materials having a basis of a lower aliphatic acid ester of cellulose and having an extensibility of 10% or less with an anhydrous medium containing from 30 .to 55% by volume of cyclopentanone in the absence of tension suificient to stretch them andremoving the medium from the materials by a washingoperation on completion of the treatment.

2. Process according to claim 1 wherein the articles impregnated have been stretched to between 3 and 5 times their original length in the presence of a stretch-assisting agent selected from the group consisting of hot water and wet steam.

3. Process for the treatment of artificial yarns, foils and similar materials, which comprises impregnating stretched yarns and similar materials I having'a basis or acetone-soluble cellulose acetate crated cellulose materials having an increased and having a tenacity of at least 2 grams per denier and an extensibility of 10% or less with an anhydrous medium containing from 30 to by volume of cyclopentanone in the absence of tension sufficient to stretch them and removing the medium from the materials by a washing operation on completion of the treatment.

4. Process for the treatmentoi artificial yarns,

foils and similar materials, which comprises im-.

pregnating stretched yarns, and similar materials having a basis of acetone-soluble cellulose acetate and having a tenacity of at least .2

. grams per denier andan extensibility of 10% tially increased extensibility and the same or less with an anhydrous medium containing from 30 to 55% by volume of cyclopentanone under such conditions that the articles are shrunk by between 2 and 10% oi. their original length 

